Rotations in the frontal plane occur around which axis?

In biomechanics, the understanding of movement planes and associated axes is crucial. Rotations in the frontal plane, which typically involve motions such as abduction, adduction, and lateral flexion, occur around the mediolateral axis. This axis runs from side to side, perpendicular to the frontal plane.

The frontal plane itself is defined by the separation of the front and back portions of the body, making the mediolateral axis the appropriate axis for analysis of rotations occurring within that plane. For instance, when performing arm movements away from the body, those rotations happen around this mediolateral axis.

It’s essential to accurately identify the relationship between the planes and axes to comprehend how the body moves in space. The other options provided do not correspond to the proper axis for frontal plane rotations, as they pertain to different movements and anatomical orientations.